A grass watering process by an irrigation system, for example a sprinkler system, usually does not produce an optimum result. Often these systems are controlled by a system timer set to run watering cycles for a fixed period of time on a list of days of the week and/or the month. At present, there is no effective device that can indicate that a sufficient water level has been reached by plant roots, and feedback this information to water electric valves.
Common irrigation systems, controlled only by a time clock, deliver water to plants and/or lawns regardless of whether the watering is needed. Recently, new devices have appeared on the market that consider several parameters in controlling irrigation systems. These parameters include ambient temperature, wind speed, day light, and predicted water absorption. Some of these devices may even connect to weather satellite links to acquire some or all of these parameters. Such devices are complex, costly, and require specialized operational skills and manual adjustments. And they still may not deliver the optimal amount of water due to lack of feedback about soil and water conditions at grass roots system.
Many moisture sensors have been designed to provide feedback from the soil. They have had limited success, because they have tended to measure the absolute soil moisture level. The main problem with such device is that soil conditions can significantly modify the readings. These changes in soil conditions may be caused by, for example, salts from fertilizers, soil compactness changes with time, leakage conductance from faulty wire splicing, and electrochemical deposition on moisture probes themselves. Any of these changes in soil conditions often requires a manual readjustment to the irrigation system controller for optimal performance.
A method and apparatus implementing that method are needed for the control of an irrigation system providing at least some, and preferably all, of the following benefits: delivering of optimum watering of the plants regardless of weather conditions; minimizing and/or eliminating over-watering reduces operating costs; minimizing and/or eliminating manual adjustments, reduces operating costs; minimal expense and minimal complexity to install.